That is a flare-bevel weld. Basically where the outer bend radius of a bend is welded to a flat plate, this area is filled with weld.
The welds are ground flat (the 'G' = grinds finish, and the horizontal line over it means flat, as opposed to convex or concave). The 30 (8) should be the depth of preparation, and the -120 being the groove weld size. Although these numebrs seem a littel off / don't look right. They might be referrring to the length of the weld bead [30], (8) welds total along the length of the part, and the -120 is the weld pitch, center to center. 8 welds, 30 long, every 120 on center.. And this would mean the numbers are on the wrong side of the symbol. Can you go see the part? And measure / validate the welds & their placement?
This is for ANSI weld symbols. ISO weld symbols possibly differ...
Paul is correct. I would suggest that you do a web search on Google or your favorite search engine for weld symbol chart. There are lots of images of charts that show the symbol and the corresponding weld joint along with diagrams of what the dimensions are used for.
